Rational design of cobaltocenium-containing polythioether type metallo-polyelectrolytes as HCl corrosion inhibitors for mild steel

Abstract

A series of cobaltocenium-containing polythioether type metallo-polyelectrolytes with different linkages and substituents were synthesized by photo-induced thiol–ene polymerization and subsequent click chemistry, and investigated as HCl corrosion inhibitors for mild steel. Given the similar structures of the polymer precursors and quantitative modification of the click reaction, the structure–property relationship of these polymeric corrosion inhibitors was systematically investigated. According to a weight loss experiment and electrochemistry study (potentiodynamic polarization and electrochemical impedance spectroscopy), it was found that these metallo-polyelectrolytes were potentially robust inhibitors, which could achieve inhibitive efficiency as high as 95% at a concentration as low as 10 mg L⁻¹. More importantly, the mechanism of these inhibitors was explored by contact angle, X-ray photoelectron spectrum and molecular dynamics simulation, revealing the important role of the flexible linkage between the main-chain and charged groups, the number of charged groups, and the presence of coordination atoms in the main chain for the design of robust polyelectrolyte-type inhibitors. The current work may provide an effective method for the rational design and preparation of robust polyelectrolyte-type inhibitors, and guidance to investigate the structure–property relationship.